HLFO - Utility Modulation Source for Eurorack - DIY Kit
The HLFO (haptic low-frequency oscillator) is a 10HP module for Eurorack modular systems. The core of the module features a voltage-controlled LFO. The rate and amplitude of the LFO can be controlled with the on-board FSR, or external control voltages can be used.
The LFO features triangle, square, and random (S&H) output waveforms. The sample and hold generator samples the HLFO's internal noise source, to generate a random waveform. The internal S&H generator has its own separate output (pre-VCA) and can sample any external voltage source by plugging into the SRC jack. The HLFO's S&H can be externally clocked by plugging into the CLK jack. The NOISE output features a white noise generator (5Vpp).
The on-board touch sensor (FSR) has an output range of 0 to 5VDC. The FSR signal is normalized to the RATE and AMP controls. Plugging into the RATE or AMP jack will disconnect the FSR from that control.
The HLFO has a rear panel jumper to select the speed range of the LFO. At the normal setting, the LFO ranges from around .25Hz to 125Hz. At slower settings, the LFO is capable of generating waveforms with periods of over 45 seconds.
This combination of functions allows for an extremely flexible waveform generation tool, LFO, noise source, sample & hold, touch controller, mod wheel interface, aftertouch interface, and more.
Schematic (Updated 12-6-17)
BOM (Updated 12-6-17)
A video demonstrating how the HLFO works:
A video of the HLFO generating various waveforms and modulating a VCF/VCO:
DIY Kits are available in 4 configurations:
1) Bare PCB + Foam Sensor Cover
2) Bare PCB/Panel/Foam Sensor Cover
3) Bare PCB/Panel/2 Song Huei Pots/2 Knobs/Foam Sensor Cover
4) Bare PCB/Panel/2 Song Huei Pots/2 Knobs/2 RV-09 Pots/SPDT Switch/8 Jacks/Foam Sensor Cover/FSR/Power Header/Power Cable
SPDT On-Off-On switches are available from Tayda electronics.
Song Huei tall trim pots are available here.
Large knobs used on RATE and AMP pots are available here.
All other parts are available at Mouser. A bill of materials and clickable Mouser cart link is available in the HLFO Builders Guide.
If you want to reduce the amount of places that you must order parts from, kit options 3 and 4 are recommended. Ordering kit option 3 or 4 means that only a Mouser order is needed to build the module. If ordering option 1 or 2, tall pots, knobs, SPDT on-off-on toggle, and FSR must be ordered from other suppliers.